The invention relates to process and apparatus for aseptically filling a package with a product under an atomosphere of sterile air containing oxygen and for removing and displacing the sterile air from the headspace of the filled package with nitrogen and for sealing the package so that the sealed, filled package headspace contains the nitrogen.
In the field of aseptic filling using certain types of machines, it is not possible to fill a package and seal it without leaving in it a small volume of gas, called headspace gas. As systems are normally used with sterile air, this headspace contains about 20% of oxygen. The presence of oxygen has a negative effect in the sense that, during preservation of the product contained in the package, it frequently happens that the product is sensitive to oxygen, which thus leads to degradation of its taste and/or of certain ingredients, such as vitamins and mineral salts. This phenomenon is unacceptable for the consumer, or for food legislation reasons.
One solution for reducing headspace air involves replacing the air with steam just before sealing. However, the drawback of this system is that the steam condenses on cold surfaces, the consequence being unacceptable risk of infection for neutral or slightly acidic products. A second solution consists in reducing the headspace by means of mechanical elements pressing the package, but it is not possible to remove the headspace air completely. German Patent Application Publication No. 31 08 817 also relates to a device enabling oxygen to be removed from the headspace of a package. In this device, the nozzle enabling the nitrogen to be injected is fastened to one of the sealing elements, thereby decreasing the efficiency of the nitrogen supplied since the nozzle moves and the stream of nitrogen changes direction. U.S. Pat. No. 4,934,127 and European Patent Application Publication No. 0 479 037 also relate to devices for removing the oxygen from the headspace of a package. The drawback of these devices is that the sealing of the package takes place downstream of the nitrogen injection station, this having the effect of allowing the quantity of nitrogen introduced beforehand to be distributed.